The Donegal TD used Dail privilege to describe how IBRC chiefs rejected three different proposals.

But when Denis O’Brien personally made a fourth attempt and it was accepted despite the fact the loans had expired.

Mr Doherty is not alleging Mr O’Brien did anything wrong but says revelations such as these should mean the actions of the liquidators must also be covered by the Commission of Investigation.

He said: “Denis O’Brien made a fourth proposal to IBRC (on 10 October 2013) for a 12-month extension with no capital repayments which was, according to the document I have, it was approved on 14 November 2013.

“This was for a loan of in excess of €315million with a margin interest rate of 3%, amounting to €10million per annum.

“How does a bank in liquidation create what is essentially a new €315million loan which its Group Credit Committee had rejected just a number of months earlier?

“Why didn’t IBRC place a call on the now expired loan? How did the verbal agreements between certain managers prior to liquidation outweigh the decision of the Group Credit Committee?”

The probe into IBRC sparked by dealings between the failed lender and billionaire Denis O’Brien will cost taxpayers €4million, it emerged.

The anticipated terms of reference of the Commission of Investigation were published by the Finance Department.

IBRC was wound up two years ago, but questions have emerged about its operations and whether it offered preferential terms to borrowers such as businessman Denis O’Brien.

The commission will look at transactions where there was a loss of an estimated €10million to IBRC or transactions identified by the commission that give rise to public concern.

Its work will cover the period from 21 January 2009 to 7 February 2013, when the special liquidators to the former Anglo Irish Bank were appointed.

Opposition parties had called for the timeline to be extended beyond February 2013.

Sinn Féin's Pearse Doherty

The terms of reference state that the commission will exercise discretion in relation to the scope and intensity of the investigation.

Following consultation with the Opposition, the terms include the role of the Department of Finance and Minister for Finance and his predecessor Brian Lenihan in relation to oversight of IBRC transactions.

It will also look at the internal governance in the bank in relation to procedures and controls and examine whether there is “prima facie evidence of material deficiencies” in the performance of those acting on behalf of IBRC, including board members, directors and management in relation to transactions.

Fianna Fáil had asked that staff of the IBRC’s wealth management unit were included and that will be part of the commission’s remit.

The interest rates, extension of interest rates or period of repayments that were given by IBRC, which resulted in a loss of more than €4 million in interest, will be examined.

Independent TD Catherine Murphy claimed in the Dail Mr O’Brien was at one time paying a low 1.25% interest rate – when most borrowers would have been expected to pay 7.5%.

Unusual share trading which would give rise to concerns of insider information being improperly provided will also be investigated in relation to the transactions.

The commission will report back by December 31, despite the fact that the Opposition had wanted it to complete its work by October.

It is estimated the investigation will cost €4 million and the Government had to agree the remit of the inquiry ahead of a Dáil debate which got underway last night.